Alkali metal salts of 2,4-dichloro-6-hydroxy-s-triazine are used as raw material for reactive dyes, as cross-linking agents for photo gelatins and recently as formaldehyde-free cross-linking agents for producing wrinkle-proof and easy-care properties of fibrous materials containing cellulose--see EP-A 0,616,071. Due to the decomposable nature of the solid triazine derivative the latter is usually not isolated but rather processed further in an aqueous phase.
It is known that cyanuric chloride can be hydrolyzed with alkali hydroxides to 2,4-dichloro-6-hydroxy-s-triazine and 2-chloro-4,6-dihydroxy-s-triazine--see Smolin and Rappoport, The Chemistry of Heterocyclic Compounds, S-Triazines and Derivatives (1967), 53-54. According to this document the hydrolysis does not stop at the desired first stage but rather the second and third chlorine atom are hydrolyzed at least partially in some instances.
According to German Patent DD 115 121, the 2,4-dichloro-6-hydroxy-s-triazine-Na salt, abbreviated in the following as DCHT-Na, is produced by the addition of cyanuric chloride dissolved in benzene or chloroform to an aqueous solution of sodium carbonate or sodium bicarbonate at 15.degree. C. The use of organic solvents and the development of C0.sub.2 from Na.sub.2 CO.sub.3 or NaHCO.sub.3 are disadvantageous. In the method according to JP-A 59-106474, 2.0 to 2.6 mol NaHCO.sub.3 are added in the hydrolysis per mole cyanuric chloride together with a buffer, e.g., a phosphate buffer.
If cyanuric chloride is to be converted into DCHT-Na by sodium hydroxide solution instead of by sodium bicarbonate, according to SU-A 1051082, a buffer is again used and the reaction carried out at pH 8.5 to 8.8. However, the buffer is frequently undesirable since the solution is processed further. In addition, there is the risk of the pH dropping to values below 7 in this method of operation on account of the limited buffer capacity and thus an increased formation of the di- and trihydroxytriazine derivatives.
K. Matsui and J. Sakomoto show in Yuki Gosei Kagaku 18 (1960), H.3, 175-183 (45-53) that for the production of 2,4-dichloro-6-hydroxy-s-triazine (DCHT-Na) sodium hydroxide solution should be added at 0 to 5.degree. C. to a suspension of cyanuric chloride. On the other hand, for the production of 2-chloro-4,6-dihydroxytriazine-Na salt (CDHT-Na) a cyanuric chloride suspension is charged into a sodium hydroxide solution. It was found during the reworking of the method described in this document that DCHT-Na can be produced in this way on a laboratory scale, but that this method poses safety problems on an industrial scale. Reaction heat is released which is difficult to control or, alternatively, the reaction rate is too slow.